Subsurface safety valves are emergency device that shut in a well. They are typically an integrated portion of a production string and are actuated through one or more control lines that run parallel to the production conduit in the surrounding annular space. Typically, these valves require pressure in the control line to hold the valve open and the valve closes on loss of or removal of control line pressure. These valves have a hinged valve member called a flapper that can pivot from being on a seat to define the valve closed position to being rotated off the seat to define the valve open position. Typically the control lines lead to an operating piston in the valve housing and that operating piston is linked to a flow tube that is biased by a closure spring. Applied control line pressure pushes the operating piston and takes the flow tube with it against the force of the closure spring. When the flow tube is forced down, it contacts the flapper that is then on the seat and rotates the flapper 90 degrees as it moves in front of the flapper so that flow can occur through the bore in the flow tube. The hinge for the flapper is biased by a torsion spring. When control line pressure is removed or lost, the closure spring releases its stored energy and pushes up the flow tube allowing the torsion spring to rotate the flapper back to its seat for the valve closed position.
Attempts in the past have been made to use alternatives to the above described basic design. One design features a separation of the control line pressure system from tubing pressure in the string, usually accomplished by resilient seals on the operating piston, by totally isolating the operating piston from the flow tube with a wall in the housing. The operating piston carries a magnet and the flow tube is magnetic with the theory being that movement of the magnet with the operating piston will urge the flow tube to operate the flapper and eliminate leak paths between the tubing and the hydraulic control system. This design is shown in U.S. Pat. No. 7,213,653.
Another design hooks the flow tube to an extending rod that is part of a solenoid type system that draws the rod into the valve body when a field is created therein from energizing a coil. This design is shown in U.S. Pat. No. 6,619,388.
Other multi-valve systems that can be separately functioned by a variety of ways including electromagnetic telemetry are described in U.S. Pat. No. 7,108,073.
What is needed and not found in the prior art is an operating system for a flapper that eliminates the need for a flow tube and associated hydraulic lines to the surface. The proposed system uses magnetic forces that can be selectively turned on and off to actuate rotation of the flapper. The torsion spring can preferably remain on the flapper hinge but its use is optional with the system. The magnetic field can be set up to either pull or push or both pull and push the flapper off its seat. Optionally, an equalizing valve in the flapper can be provided that initially responds to a magnetic opening force to equalize pressure before enough force is developed to pull the flapper off the seat. These and other features of the present invention will be more apparent to those skilled in the art from the description of the preferred embodiment and associated drawing that appear below, while recognizing that the scope of the invention is defined by the appended claims.